With an increasing recording capacity of a digital recording medium, such as an optical disc, and with coming into popular use of this sort of the recording medium, it becomes necessary to take measures against unauthorized copying of signals recorded on the recording medium, in order to protect the copyright of the recorded signals. That is, if the signals are digital audio data or digital video data, duplications free of data deterioration can be easily produced by copying or dubbing from the digital data or the digital signals. In the case of data handled by a data processing apparatus, such as a computer, the data which are the same as the original data can be easily obtained on copying or dubbing, so that troubles such as infringement of the copyright by such unauthorized copying have already come to the surface.
In this consideration, data indicating preset copying inhibition may be recorded in an original digital recording medium, in order to prevent the aforementioned unauthorized copying in so-called digital dubbing in which digital signals recorded on a digital recording medium and reproduced are re-recorded on another digital recording medium.
For example, in a system for preventing unauthorized copying as used in the digital audio signal recording and/or reproducing apparatus termed R-DAT (Rotary Head Digital Tape Recorder), an inhibiting code for inhibiting digital copying or serial generation copying by way of so-called generation limitation (Serial Copy Management System or SCMS) is recorded in a main data area for digital audio signals recorded on a digital audio tape as the digital recording medium. If, in recording, the digital audio signal recording apparatus has detected this inhibiting code, recording by copying of the digital audio signals, contemplated to be copied on a new digital audio tape, is inhibited.
In a dubbing system in which digital signals reproduced from signals recorded on a digital recording medium are re-recorded on another digital recording medium, it is sometimes attempted to protect the copyright by limiting the number of copies of the contents on digital recording mediums.
Meanwhile, if such limitation of the number of copies of the contents on the digital recording medium is to be made on the basis solely of the content identification information, the number of the copies of the contents is not larger than the allowed number of copies even if the user owns plural digital recording mediums having the same contents recorded thereon. That is, the recording apparatus, supplied with the same content, has already memorized that the recording of the contents has already been made, but cannot distinguish from which recording medium the contents now to be recorded is originated. Consequently, the apparatus cannot produce the number of copies which is more than the number allowed for given contents.
The conventional copying management system is not designed so as to control the outputting of the content data on the part of the reproducing apparatus reproducing the digital recording medium, so that it has been difficult to construct a system operating in such a manner as to reliably inhibit unauthorized copying of content data.